不同衰老类型小麦品种在衰老过程中光合特性的变化

以衰老类型不同的两个小麦品种鲁麦L14和935031为材料,研究了不同衰老类型小麦品种在衰老的过程中光合特性的变化。结果表明:自开花至成熟期,鲁麦L14小麦叶片光合速率、叶绿素含量、可溶性蛋白含量及光能转化效率的下降速度均明显快于小麦品种935031,但是各相关参数降低的起始时间不同,自开花后30 d鲁麦L14的叶片已经开始干枯,而935031小麦品种到成熟时大部分叶片还保持绿色,说明小麦叶片早衰与光合能力的下降有密切关系。     

小麦品种衰老类型的比较研究

在1981～1985年期间对4个不同衰老类型的小麦品种进行了比较研究。各类型的主要表现为:正常衰老的北京17号,旗叶、2叶的蛋白质含量、叶绿素总量及 a/b 比率保持稳定的时间长,非蛋白质氮含量低,蛋白质氮/非蛋白质氮比率高,衰老时从叶片转运出的氮也最多。这是一种合理的冠层结构的表现。青枯型早衰的京矮20,叶绿素和非蛋白氮的     

硝酸还原酶活性与小麦叶片衰老及粒重的关系

研究了3个品种小麦开花后，旗叶硝酸还原酶（NR）活性变化、旗叶衰老及其与籽粒增生的关系。结果表明，小麦开花后，NR活性首先升高然后再下降；NR的活性与籽粒粒重之间相关不显著。但NR活性变化与籽粒灌浆速率间显著相关；旗叶衰老，旗叶叶绿素,含量、可溶性蛋白质含量和绿叶面积一粒增重显著负相关。皖18、蒲麦8441开花后植株早衰明显，千粒重低，矮旱781植株衰老畔慢，千粒重高。     

不同水分条件下小麦持绿表型性状评价及其与产量相关性研究

找出适宜在多个环境条件下评价小麦持绿性状的表型指标,为快速筛选小麦持绿品系,加速抗旱、高光效育种进程提供数据支撑。以包含306个家系的RIL群体（旱选10号×鲁麦14）为材料,分析了不同水分条件下灌浆不同时期旗叶叶绿素SPAD值、功能绿叶面积持续期（GLAD）以及衰老参数变化特征,并对其与产量性状的相关性进行了研究。结果表明：RIL群体SPAD值、GLAD在整个灌浆期的变化动态复杂,衰老相关参数无法反映其动态变化过程。2种水分条件下,在灌浆后期（花后20、25和30d）SPAD值与粒宽、粒厚、千粒重以及单株产量呈显著或极显著正相关。在灌溉条件下花后10、13、16、19和22d的GLAD与单株产量呈极显著正相关;而在干旱胁迫条件下GLAD与单株产量相关性则未达到显著水平。不同环境条件下,旗叶SPAD值在灌浆后期（花后20、25和30d）相比于GLAD和衰老特征参数与产量性状具有更好的相关性,且测定相对简单,更适宜于持绿品系的快速筛选。     

低氮诱导小麦灌浆期旗叶衰老与膜脂的关系

小麦产量主要来自于小麦灌浆期旗叶的光合产物, 低氮造成的灌浆期旗叶早衰对小麦产量影响极大。本试验以小麦品种“长旱58”为试验材料, 在大田环境下设置低氮(120 kg hm ^-2)和正常氮(180 kg hm ^-2)处理, 研究低氮诱导的小麦旗叶衰老与膜脂的关系。结果表明, 开花14 d后, 低氮处理小麦旗叶的光合速率、叶绿素含量、旗叶总氮含量均显著降低; 旗叶中膜脂各组分含量均显著下降, DGDG/MGDG的比值升高; 以C18:3、C18:2为代表的不饱和脂肪酸含量显著下降, 以C16:0为代表的饱和脂肪酸含量显著增加, 不饱和双键指数显著降低; 此外类囊体蛋白质堆积密度也显著降低。综合分析认为低氮处理导致小麦灌浆期旗叶早衰, 早衰过程伴随着膜脂降解和组分改变, 降低了膜的流动性和通透性, 导致叶绿素降解, 使光合功能受损。同时, 植物通过调整DGDG/MGDG比例来响应低氮胁迫, 利用DGDG的双层特性来部分弥补其它双层膜脂的降解对膜功能造成的损伤。     

小麦叶面积及光合速率与产量关系的研究

选用不同叶片姿态、不同叶片类型以及不同经济系数等多种特性小麦品种(品系)以及拟近等基因系为试验材料,测定了不同叶位叶面积、旗叶光合速率以及小麦生物和经济产量。研究小麦叶面积、旗叶光合速率与产量的关系。结果表明:顶三叶面积与单株生物产量、经济产量显著正相关,而下部三片叶叶面积与单株生物产量和经济产量之间无显著相关;旗叶光合速率与生物产量和经济产量之间呈正相关,但相关不显著,而旗叶光合速率与旗叶面积的乘积与生物产量和经济产量之间呈显著正相关。提高小麦顶三叶面积和光合速率有利于提高产量,旗叶面积和光合速率乘积与产量的关系更为密切。     

玉米持绿与早衰品种叶片衰老过程中光化学活性的变化

为了探讨不同衰老型玉米叶片在衰老过程中光化学反应及其对光合能力维持的贡献, 本研究使用持绿玉米品种“齐319”和早衰玉米品种“黄早四”, 在控制的条件下, 用乙烯利诱导离体叶片衰老, 通过快速叶绿素荧光诱导动力学曲线(OJIP曲线)和820 nm光吸收等技术, 研究了衰老过程中叶片叶绿素含量、光合速率、光系统I (PSI)、光系统II (PSII)以及光合电子传递体活性的变化。结果表明, 在衰老过程中, 齐319叶片叶绿素含量和光合速率的下降速度明显慢于黄早四, 是功能型持绿品种。玉米叶片的衰老伴随着OJIP曲线的J、I、K、L点荧光的增加, 以及远红光诱导820 nm光信号落差的下降。与齐319相比, 黄早四叶片的OJIP曲线和820 nm光吸收曲线的变化更剧烈。我们认为, 在衰老过程中PSI和PSII光化学活性的快速下降和光合电子传递功能的衰退是玉米叶片光合能力迅速下降的重要原因之一。在此基础上, 讨论了衰老过程中玉米叶片中与光合作用有关蛋白与光合能力下降的可能关系。     

不同品种玉米籽粒成熟期间叶片形态衰老的差异

试验研究了紧凑型玉米郑单958和平展型玉米农大364在籽粒灌浆、成熟过程中叶片衰老的形态变化.在灌浆期内,两个品种植株下部和顶部叶片的衰老进程明显快于中部叶片,并且平展型玉米的表现更为明显.两个品种穗位叶以上叶片的衰老程度具有明显差异,成熟期时,除了第17、18两叶以外,平展型玉米各叶位叶片的衰老比例均高于紧凑型玉米,致使其单株叶面积显著低于紧凑型玉米.籽粒灌浆后半阶段叶片的衰老速率显著高于前半阶段,平展型玉米在灌浆后半阶段叶片的衰老速度明显高于紧凑型玉米,这可能是引起两个品种单株产量差异的原因之一.有效缓解灌浆后半阶段顶部叶片的衰老将有助于提高玉米产量,特别是平展型玉米.     

冬小麦品种间旗叶衰老特性的比较

本文研究冬小麦开花后旗叶净光合速率的变化规律，分四种类型：急降型、快降型、稳降型、缓降型。进行系统聚类分析，18个品种可分为三类－－正常衰老、轻度衰老、严重衰老。又根据旗叶与籽粒灌浆成熟的关系，比较两个典型品种鲁麦14、215953，得出结论：①根据小麦的不同品种特性，采取相应的栽培措施。②提高小麦产量关键不是一味延长生育期，而是要采取诱导延长高水平的净光合速率。     

外源ABA和6-BA对不同持绿型小麦旗叶衰老的影响及其生理机制

为深入认识植物激素在小麦抗氧化和调控衰老中的作用机制,以持绿品种汶农6号和非持绿品种济麦20为材料,在盛花期后喷施脱落酸(ABA)和6-苄基腺嘌呤(6-BA),考察外源激素对旗叶衰老过程中生理生化指标动态变化以及籽粒产量的影响,并探讨了激素与衰老的关系。结果表明,汶农6号旗叶的超氧化物歧化酶(SOD)和过氧化物酶(POD)活性、叶绿素含量及籽粒千粒重和产量均大于济麦20,且丙二醛(MDA)含量低于济麦20,表明持绿型品种抗氧化能力强,衰老进程较慢,进而获得较高产量。外源ABA和6-BA处理显著提高花后7~28 d旗叶叶绿素含量,提高花后21~35 d可溶性蛋白含量,显著降低花后28~35 d旗叶MDA含量。外源ABA降低两品种旗叶玉米素(ZR)含量,但提高生长素(IAA)和赤霉素(GA)含量,降低了其在花后28~35 d的ABA含量。6-BA处理提高旗叶ZR含量及花后7~14 d IAA含量,降低济麦20花后21~35 d旗叶ABA含量。外源ABA显著提高汶农6号花后7~21 d旗叶SOD活性,喷施ABA对汶农6号旗叶POD和过氧化氢酶(CAT)活性影响没有显著性影响,但显著提高了济麦20花后7~28 d POD活性,喷施6-BA提高了两品种7~28 d SOD、POD和CAT活性。总之,ABA和6-BA处理改变了旗叶内源激素水平,提高抗氧化酶活性,降低MDA含量,延缓旗叶衰老,从而提高了籽粒产量。     

Stay green trait: variation, inheritance and its association with spot blotch resistance in spring wheat (Triticum aestivum L.)

One thousand four hundred and seven spring wheat germplasm lines belonging to Indian and CIMMYT wheat programs were evaluated for stay green (SG) trait and resistance to spot blotch caused by Bipolaris sorokiniana during three consecutive crop seasons, 1999–2000, 2000–2001 and 2001–2002. Disease severity was recorded at six different growth stages beginning from tillering to late milk stage. SG trait was measured by following two approaches: difference for 0–9 scoring of green coloration (chlorophyll) of flag leaf and spike at the late dough stage (GS 87) and a new approach of leaf area under greenness (LAUG). Germplasm lines showed a wide range (7–89) for LAUG and were grouped into four viz., SG, moderately stay green, moderately non-stay green and non-stay green (NSG). However, very few (2.2%) lines showed high expression of SG trait, i.e., LAUG >60. LAUG appeared to be a better measure of SG trait than a 0–9 scale. Mean spot blotch ratings of SG genotypes were significantly lower than those of NSG genotypes at all growth stages. Two spot blotch resistant genotypes (Chirya 3 and Chirya 7) having strong expressions of SG trait were crossed with NSG, spot blotch susceptible cv. Sonalika. Individually threshed F₂ plants were used to advance the generations. SG trait and spot blotch severity were recorded in the parents and F₁, F₃, F₄, F₅, F₆ and F_6–7 generations under disease-protected and inoculated conditions. SG trait in the F₁ generation was intermediate and showed absence of dominance. Evaluation of progenies (202–207) in the segregating generations revealed that SG trait was under the control of around four additive genes. Lines homozygous for SG trait in F₄, F₅, F₆ and F_6–7 generations showed significantly lower mean area under disease progress curve (AUDPC) for spot blotch than those with NSG expression. A positive correlation (0.73) between SG trait and AUDPC further indicated a positive influence of SG on severity of spot blotch. The study established that variation for SG trait exists in spring wheat; around four additive genes control its inheritance in the crosses studied and there is positive association between SG trait and resistance to spot blotch.     

Mapping and validation of the quantitative trait loci for leaf stay‐green‐associated parameters in maize

Functional stay‐green is generally regarded as a desirable trait of varieties in major crops including maize. In this study, we used an F_3:4 recombinant inbred line population with 165 lines from a cross between a stay‐green inbred line (Zheng58) and a model inbred line (B73) using 211 polymorphic simple sequence repeat markers to map quantitative trait loci for three stay‐green‐associated parameters, chlorophyll content, photosystem II photochemical efficiency and stay‐green area, at maturity stage, detected a total of 23 quantitative trait loci (QTL) on nine chromosomes. Single QTL explained 3.7–13.5% of the phenotypic variance. Additionally, we validated some important stay‐green QTL using a heterogeneous inbred family approach and found that the stay‐green‐associated parameters were significantly correlated with the plant yield. This study may contribute to a better insight into the regulatory mechanism behind leaf stay‐green in maize and a novel development of elite maize varieties with delayed leaf senescence through molecular marker‐assisted selection.     

不同高油花生品种(系)油分积累特性的模拟研究

为了准确了解油用型花生籽仁油分积累特性, 筛选适合描述花生籽仁油分累积特性的生长模型, 以6个高油花生品种(系)为材料, 用Richards、Logistic和Gompertz方程拟合了花生籽仁油分累积特征曲线。研究结果表明, Richards方程能够较好地拟合不同花生品种(系)的油分累积特性, 其拟合度优于Logistic和Gompertz方程。不同花生品种(系)间油分累积特性的比较研究结果表明, 籽仁脂肪含量的变化过程基本可以划分为初始积累、快速积累和稳定积累3个阶段, 油分积累主要集中在前2个阶段。提高含油量有提高油分积累速率和延长油分积累持续时间2策略。提高籽仁油分最大积累速率、初始积累阶段油分积累量和快速积累阶段油分积累量是增加籽仁含油量的关键。     

Responses to N Deficiency in Stay Green and Non‐Stay Green Argentinean Hybrids of Maize

Breeding has developed better yielding maize hybrids for low N environments, which also have delayed leaf senescence (‘stay green’ trait, SG). Here, we studied whether the SG trait can further improve yield of modern hybrids under N‐limiting conditions. In two field experiments, four maize hybrids with different senescence behaviour were grown under three N fertilization levels, from 0 to 200 kg N ha^?1 (N0, N100 and N200). After silking, hybrids differed for senescence depending on the canopy layer (P < 0.05): the SG AX878 only delayed senescence at the mid and upper canopy layers while the SG NK880 delayed senescence of all layers. Across N doses, higher yields were achieved by both SG hybrids, AX878 and NK880 (P < 0.05) but yield was not only determined by senescence behaviour. Kernel weight (KW) response to N availability was larger for SGs than for their non‐‘stay green’ counterparts. Delayed senescence in SG hybrids was not related to higher post‐silking N uptake but to higher (P < 0.05) %N in leaves and lower (P < 0.05) %N in kernels at harvest (below the critical 1.1 % under N deficiency). Across N levels, KW positively related to N content per kernel, with a steeper slope (P < 0.05) for the SG hybrids. Taken together, our results suggest that a condition where N limits kernel growth, in a scenario of saturating C availability, may be common to stay green genotypes of maize.     

施氮水平对不同种植模式小麦旗叶衰老和产量的影响研究

摘要：①氮素水平与小麦后期旗叶衰老有着密切关系。中氮和高氮处理与低氮和无氮处理相比,显著提高了SOD和POD的活性,相对改善了细胞中活性氧产生与清除之间的平衡,减少了细胞内过氧化物的积累,减缓了叶片衰老;但平作栽培小麦264 kg .hm-2水平（N3处理）与165kg .hm-2水平（N2处理）间的SOD、POD活性、MDA含量以及叶绿素含量等生理指标差异不显著,表明施氮量达到一定水平后继续增加施氮量对延缓小麦旗叶衰老无显著效应。②通过对垄作和平作两种栽培模式的比较发现,小麦旗叶衰老进程分为两个阶段;平作小麦以花后14天,垄作小麦以花后21天为拐点,前期为缓慢衰老期,后期为急剧衰老期。在缓慢衰老期,旗叶POD、SOD活性,叶绿素含量会略有上升;而进入急剧衰老期后,上述三个生理指标都急剧下降。平作小麦比垄作小麦提前进入急剧衰老期。③氮素水平为165kg .hm-2时,两种栽培模式均可以获得中产以上产量;264 kg .hm-2水平下能够获得更高的产量,且垄作栽培小麦的增产优势较平作小麦更明显。     

Stay green trait in grain sorghum: relationship between visual rating and leaf chlorophyll concentration

Post‐flowering drought tolerance is referred to as the stay green trait in sorghum. Plants with stay green resist drought‐induced premature plant senescence. In breeding programmes, stay green is evaluated under limited irrigation, post‐flowering moisture‐stress field conditions and visually scored at or soon after physiological grain maturity. The objective of this study was to investigate the relationship between the stay green rating and total leaf chlorophyll content. The parents B35 and Tx7000, and their 98 F, recombinant inbred lines were evaluated in replicated field trials under limited (post‐flowering stress) and full‐irrigation (non‐stress) conditions. After scoring the stay green trait of stressed plants, total leaf chlorophyll contents were measured with a chlorophyll meter (SPAD values) and a spectrophotometer method. The SPAD value had a significant linear relationship with total leaf chlorophyll (R²= 0.91) and with visual stay green rating (with R²= 0.82). Relative water content in top leaves of the stay green lines was about 81%, much higher than non‐stay green lines (38%), indicating that the stay green lines kept the stalk transporting system functioning under severe drought conditions, The results indicate that visual stay green ratings were a reliable indicator of leaf senescence an should be useful to sorghum breeders in evaluating progeny when breeding for drought tolerance.     

Carbon and nitrogen allocation and grain filling in three maize hybrids differing in leaf senescence

Between flowering and maturity, leaf senescence reduces green leaf area while grains are filled from photosynthesis, nitrogen (N) uptake by roots and remobilisation from shoots. The question arises of possible effects of leaf senescence on photosynthesis, N uptake and remobilisation and their modification through genetic variations in senescence. To address this question, we compared three cultivars showing different behaviours. Tarro and Nicco are two modern hybrids presenting the same important grain sink but showing different time course of senescence, the former being normally senescent the latter “stay-green”. Déa hybrid, very well known by many previous experiments was the reference hybrid.The purpose was to monitor precisely the carbon (C) and N repartition in the main organs of the plant in connection with the progress of leaf senescence (experiment 1) and to measure the changes created by variations of N supply and soil-climate conditions (experiment 2).In experiment 1, time course of leaf senescence of the different leaf stages and weight of leaves, shoots and grains and N concentration of shoots and grain were measured weekly. In experiment 2, the same three cultivars were grown at limiting and non-limiting N supply in four locations in France during 2 years. At flowering, silage and harvest stage, dry matter and N concentration were measured in the main parts of the plant, and leaf senescence was evaluated at silage stage.On soil well supplied with N, Tarro had an identical rate of leaf senescence than Nicco for leaves below the ear, but higher for leaves above the ear. After flowering, Nicco accumulated more biomass than Tarro, but kept a larger part of this total biomass in the stem. In contrast, Tarro accumulated a larger part of total biomass in the grain.After flowering, N uptake was larger in Nicco than Tarro. Shoot N concentration decreased earlier and more completely in Tarro than Nicco, indicating a larger remobilisation to the grain. Though Tarro began and finished grain filling simultaneously with Nicco, it reached 70% of final grain weight 25 °C d sooner than Nicco.The senescence due to N stress differed from the physiological senescence of a senescent hybrid. The time course of the reproductive phase and the N repartition in the plant suggest that a threshold in grain filling or in shoot nitrogen decrease could be the internal signal triggering senescence of uppermost leaves.     

抽穗后冬小麦旗叶光合特性的变化对产量的影响

为了探讨不同小麦品种之间的光合特性的差异及光合作用与经济产量的关系,本研究选取4个不同冬小麦品种分别在6个生育时期进行了光合特性的测定。结果表明：小麦旗叶6项光合特性指标随发育进程变化的趋势、变化程度基本相同,但不同品种在不同发育时期内光合特性指标的数值、变化程度不同;6项光合特性指标均与籽粒产量正相关;相关程度表现为绿叶面积>气孔导度>胞间CO₂浓度>净光合速率>叶绿素含量>蒸腾速率;不同时期光合特性与籽粒产量的相关性顺序为灌浆中期>灌浆前期>灌浆后期>开花期>抽穗期>灌浆末期;在开花期至灌浆后期,维持和提高旗叶的绿叶面积、叶绿素含量、净光合速率、气孔导度、胞间CO₂是提高小麦产量的基础。因此,在开展小麦高光效育种时,对种质资源材料进行光合特性测定和比较对育种工作具有非常重要的参考价值和指导意义。     

Cytokinins: A key player in determining differences in patterns of canopy senescence in Stay-Green and Fast Dry-Down sunflower (Helianthus annuus L.) hybrids

Leaf senescence during grain filling can reduce crop yield. We studied, under field conditions and during grain-filling, the association between leaf cytokinin levels and the onset of leaf senescence in sunflower hybrids of contrasting canopy senescence patterns (Paraiso75, stay-green [SG] and Paraiso65, fast dry down [FDD]). At crop level, dynamics of live root length density (LRLD) and green leaf area index (GLAI) were followed, while at leaf level dynamics of total chlorophyll content, trans-Zeatin content, net photosynthesis and PSII quantum yield, were followed in leaf positions 17, 20, 22 and 24. Responses of these leaf variables to exogenous cytokinin applications to leaves at position 17 were also followed. SG exhibited greater (p < 0.05) LRLD and GLAI values at anthesis. In both hybrids, LRLD began to fall before GLAI. All variables decreased earlier (p < 0.05) in FDD. Initial leaf levels of trans-Zeatin were three times higher (p < 0.05) in SG. Exogenous cytokinin applications maintained leaf-level variables. These are the first results showing associations between LRLD dynamics with the dynamics of leaf cytokinin levels and changes in indicators of leaf functionality. Also, this is the first study in which estimates are made of cytokinin thresholds below which leaf senescence begins in two hybrids of contrasting canopy senescence patterns. These advances in the understanding, at both crop and leaf levels, of the controls and consequences of SG during grain filling, a trait known to improve crop water uptake under drought and increase biomass accumulation during grain filling, provide support for breeding efforts aimed at profiting from this trait to increase crop yields.     

Identification of QTLs for stay green trait in wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) in the ‘Chirya 3’ × ‘Sonalika’ population

Stay green or delayed senescence is considered to play a crucial role in grain development in wheat when assimilates are limited. We identified three QTLs for stay green on the chromosomes 1AS, 3BS and 7DS using a recombinant inbred (RI) population developed by making crosses between the stay green parent ‘Chirya 3’ and non-stay green ‘Sonalika’. The RI lines were evaluated in natural field conditions for 2 years in replicated trial. The QTL on chromosome 1A was identified in both the years, while the QTLs on 3BS and 7DS were identified only in 1st and 2nd year, respectively. The QTLs explained up to 38.7% of phenotypic variation in a final simultaneous fit. The alleles for higher stay green values derived from the stay green parent ‘Chirya 3’. The QTLs were named as QSg.bhu-1A, QSg.bhu-3B and QSg.bhu-7D. The QTL QSg.bhu-3B and QSg.bhu-7D were placed in the 3BS9-0.57-0.78 and 7DS5-0.36-0.61 deletion bins, respectively.